This spring, an acquaintance asked me how she could sterilize her garden. I asked her what her purpose was. She had already been worried about weeds and insects when someone told her that she probably even had bacteria in her garden. She explained that the word “bacteria” made her skin crawl.
Bacteria need a good public relations firm to repair their reputation. No other group of living things has been so universally maligned. Mention bacteria and people immediately think of germs, cholera, typhoid fever, TB, syphilis, anthrax, leprosy, diphtheria and tetanus. Yes, these are all bacterial diseases, and they’re all nasty. We might think that the only good bacteria are dead bacteria. However, our world without bacteria would mean the end of our world. Bacteria are the mortar that holds the entire web of life together.
Bacteria are microscopic, single-cell living organisms. They live in every environment on earth and are critical to all life. Because they can only be seen under a microscope, they were unknown until discovered in the middle of the 17th century by a Dutch lens grinder, Antony Leeuwenhoek. What he found with the simple microscope he had built revolutionized biology and ushered in the new science of microbiology.
In the soil and the oceans, bacteria play a critical role in the decomposition of organic matter. They break it down so that the constituent parts can be used by other living organisms. Bacteria are the prime movers in cycling some of the basic elements necessary for life, like nitrogen and carbon, making them available to plants and animals.
Elemental nitrogen constitutes 80% of our atmosphere, but plants can’t use elemental nitrogen. Bacteria and cyanobacteria (blue green algae) transform elemental nitrogen into ammonium and nitrates that plants can use.
Carbon is also essential to life. Many bacteria play a key role in CO2 fixation. The CO2 they give off goes back into the atmosphere and is picked up by marine autotrophic bacteria which synthesize inorganic carbon into the building blocks of organic matter. That organic matter then goes up the food chain providing the carbon that all living organisms need.
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The oxygen we breathe was the gift of bacteria. Over a billion years before plants developed on earth, marine bacteria and cyanobacteria were giving off oxygen as a byproduct of photosynthesis, increasing atmospheric oxygen from less than 1% to a level that could sustain plant life. Then over millions of years, photosynthesizing bacteria and plants worked together to bring the oxygen level to our current 19%.
Scientists estimate that there are some 10 trillion cells in each of our bodies. However, they also estimate that there are ten times as many bacterial cells on or in our bodies. While there are some nasty bacteria on our skin and in our nose and throat, most of the bacteria in those areas play a protective role, devouring nasty bacteria. In our digestive system, bacteria break down our food, making nutrients available for our use. Antibiotics can wipe out those beneficial intestinal bacteria, creating many digestive problems.
Scientists often caution against the overuse of hand sanitizers and antibacterial soaps. They argue that in the process of killing a few dangerous bacteria, we are also killing millions of protective bacteria. There is evidence that early exposure to bacteria, both benign and harmful, helps the immune system develop its defenses against intruders and that sheltering children from that exposure increases their risk of later problems from invading pathogens. Research conducted at Johns Hopkins Medical School has shown that children sheltered from bacteria are at greater risk of developing allergies and asthma.
A crusade against bacteria poses another danger. Bacteria are the fastest and most prolific reproducers in the biosphere. According to Ann Maczulak, author of the eye-opening Allies and Enemies: How the World Depends on Bacteria, the total number of all bacteria on earth is astronomical, approaching 1030 or more than 2000 times the mass of all 6.5 billion people on Earth. Because they reproduce very fast and in staggeringly large numbers, bacteria also evolve much faster than other life forms. As we try to defeat pathogens with antiseptics and antibacterial drugs, those pathogens are in the process of mutating, far too often into drug-resistant progeny that stand up to our arsenal of drugs. Our misguided campaign against bacteria may be inadvertently creating new super-pathogens that we are powerless against.
Bacteria do far more good than harm. As I told the young woman who worried about bacteria in her garden, “You have billions of bacteria in your garden and be grateful you do.”